JET

JET

Would there be any fuel savings achieved by setting back the room thermostat at night in a radiant floor heating system?

Jean-David Beyer

If your house is like mine ...

... then the answer is NO. Mine has copper tubing in a concrete slab. The thermal mass is so great that the building does not cool down much until the next morning, and then when the setback ends, it takes until the evening to satisfy the thermostat again. So if I were going to do this, I would set back during the day when I am awake and set to heat at night so it will be warm in the morning.



My current boiler has outdoor reset and I think this will do better than setback because without outdoor reset, the temperature swings went from a little too cold to way too hot, and that problem seems now to be ended. It has only been very cold a couple of days so far this season so far, and it is my first heating season with this new boiler, so the votes are not yet all in.

JET

Radiant night time set back

I am having a debate with a friend who insists that I would save fuel if I set back my room thermostat at night.  I have a Buderus boiler with outside sensor and ecomatic control that sets my boiler water temperature based on outside air.  I leave the control on daytime mode so that I will produce DHW for my Aprilaire humidifier at night.  I feel that you would burn more fuel trying to bring the flooring back up to temperature than you would if you were just maintaining floor temp that was already brought up to desired temp.

Gordy

It depends

 There has been a lot of debate on this very topic at this site over the years.



If you have a poorly insulated house, then yes there would be a benefit. Or if you are going to be on vacation



Remember not only the floor mass needs to be brought up to temp. The room, and objects themselves need their mass recharged. The thermostat may get satisfied but you may experience a "cold 70" until the MRT in the room is there.



You could experiment to see how much temp you lose when in set back over an 8 to 12 hour period with outside temp of 20. If you lose over 5 degrees you may need to tighten the joint up a bit.



None the less if you, and the friend are going to compare using your own dwellings there are many other factors that can come into play.  Solar influence, wind breaks, indoor temp setting, outdoor temps, Lighting, and appliance usages, number of people, Number of entry and exits, heating plant size, type of heat.  All need to be apples to apples if you are going to compare.



I myself have found that there is no benifit for my lifestyle, and what we like for comfort, and comfort is really what its all about. My boiler runs for maybe an hour through the night when its in the 20's that translates to 1.15. That being said you could say I would save 34 bucks a month.  But I would have to replace that heat to get back up to normal setting by morning so a btu lost is a btu needed so they cancel out.





Gordy

JET

Thanks for you input

JD and Gordy thanks for your input your thoughts are similar to mine.  I was hoping there was some kind of engineering study that was done on this so that I may prove my point.  Thanks, JET